Also note the behavior is the same for a non-list vector:
> c(b=1)[c('a','b')]
<NA> b
NA 1
but differs for a data frame:
> data.frame(b=1)[c('a','b')]
Error in `[.data.frame`(data.frame(b = 1), c("a", "b")) :
undefined columns selected
On Fri, Nov 28, 2008 at 2:03 PM, Vadim Ogranovich
<[EMAIL PROTECTED]> wrote:
> Dear R-devel,
>
> When a character vector is used to subscript a list and when some of the
> subscripts are not present in the list names R returns NULL for those
> subscripts and generate NA names for each of them:
>
>> list(b=1)[c('a','b')]
> $<NA> <<-- generated name
> NULL
> $b
> [1] 1
>
>
> Wouldn't it be more intuitive to use the subscript name rather than to
> generate an NA? Something like this (not real result):
>> list(b=1)[c('a','b')]
> $a <<-- more intuitive name
> NULL
> $b
> [1] 1
>
>
>> version
> _
> platform i386-pc-mingw32
> arch i386
> os mingw32
> system i386, mingw32
> status
> major 2
> minor 7.1
> year 2008
> month 06
> day 23
> svn rev 45970
> language R
> version.string R version 2.7.1 (2008-06-23)
>>
>
>
> Thanks,
> Vadim
>
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